On March 19, 2010 I met Lyn Greenaway to check out a reported old growth forest patch in Bald Eagle State Forest in southern Clinton County, Pennsylvania. The area contains a nice section of hemlock, but I must report we did not find anything I would call old growth.
Of note in the stand is the presence of Hemlock Woolly Adelgid infesting many of the hemlocks. HWA is an invasive insect originally from Asia that has devastated the bot eastern and carolina hemlocks across southeastern United States. The insect is moving northward and westward leaving vast areas of dead hemlock snags behind. I did not see any mortality from the HWA at this site. It usually kills the older and bigger trees first. The younger trees seem more resilient and survive longer before succumbing to the pest. Many of the trees even in early spring had foliage significantly thinned by the HWA. The full trip report is here: http://www.ents-bbs.org/viewtopic.php?f=149&t=317 I included some 600 x 450 photos of the thinned foliage on the hemlocks and some close-ups of the egg sacs on the hemlock twigs.

Wilkipedia http://en.wikipedia.org/wiki/Hemlock_woolly_adelgid notes: "The presence of HWA can be identified by its egg sacs, which resemble small tufts of cotton clinging to the underside of hemlock branches. Hemlocks stricken by HWA also tend to have a grayish-green appearance, whereas healthy hemlocks are dark green. Hemlock woolly adelgid reproduces asexually and can have two generations per year. Between 100 and 300 eggs are laid in the woolly egg sacs beneath the branches. Larvae emerge in spring and can spread on their own or with the assistance of wind, birds and/or mammals. In the nymph state, the adelgid is immobile and settles on a single tree."

One problem when I was developing the Hemlock Wolly Adelgid section of the ENTS website http://www.nativetreesociety.org/tsuga/index_hwa.htm was finding good photos of the HWA infestations. I am attaching a larger scale photo of the eggs sacs below. The close-ups in the previous post are actually crops taken from this larger image. Feel free to download and use this photo.

Edward Frank

"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

Unfortunately that is not the farthest extent. it keeps spreading westward. Here are some diagrams from the PA DCNR 2009 Forest Insect and Disease Conditions in Pennsylvania document that came out in January 2010.

pa_hwa2009aa.JPG (11.8 KiB) Viewed 987 times

"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky